Of all the arguments against voluntary euthanasia, the most influential is the 'slippery slope': once we allow doctors to kill patients, we will not be able to limit the killing to those who want to die. Peter Singer
Torture is such a slippery slope; as soon as you allow a society or any legal system to do that, almost instantly you get a situation where people are being tortured for very trivial reasons. Iain Banks
There is nothing in the world that I loathe more than group activity, that communal bath where the hairy and slippery mix in a multiplication of mediocrity. Vladimir Nabokov
Once you put human life in human hands, you have started on a slippery slope that knows no boundaries. Leon Kass
It's hard to get out of the barrel. It's slippery around the edges and people are happy to see you fall back in. Robert Downey, Jr.